Problem with VPN connections throught a ISA 2006 server

My organization has a ISA Server 2006 as a firewall, working with two interfaces, internal and external. We have internal computers establishing VPN connection with other external VPN servers, but when the other VPN end is a Zyxel router/firewall, the VPN can not be established, showing error 619 on the origin (the Windows XP computer trying to establish a PPTP VPN). If we stop the ISA Server and configure our router to work without the ISA Server, this VPN connection is established without problem. We allways use NAT.

Some of you may have heard that SonicWALL has finally released an app for iOS devices giving us long awaited connectivity for our iPhone's, iPod's, and iPad's. This guide is just a quick rundown on how to get up and running quickly using the app.
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There are several problems reported according slow link speeds or poor performance in TMG 2010, UAG 2010 or ISA 2006. I want to collect here some of the common issues together to give a brief overview what can be the reason. Nevertheless, not all of…

After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…

Windows 10 is mostly good. However the one thing that annoys me is how many clicks you have to do to dial a VPN connection. You have to go to settings from the start menu, (2 clicks), Network and Internet (1 click), Click VPN (another click) then fi…